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Finite element analysis of residual-stress-induced flatness deviation in banded carbon seals

2002; Elsevier BV; Volume: 38; Issue: 9 Linguagem: Inglês

10.1016/s0168-874x(01)00105-6

1872-6925

Rahul N Samant, Patrick E. Phelan, M. Rifat Ullah,

Tribology and Wear Analysis

Carbon face seals, used in the aircraft engines manufactured by AlliedSignal Engines, are assembled via a shrink-fit procedure which generates residual stresses in both components, resulting in 30–50% of the seals not meeting the required flatness tolerance of three helium light bands (3 HeLB, equal to 0.762μm). A two-dimensional, axisymmetric finite element analysis is carried out here to provide a means for better understanding the geometric and processing parameters of the face seals in order to improve their flatness. Results indicate that to obtain a lower value of fd, the flatness deviation, the seal should have a larger inner radius (Ri), a smaller initial radial interference (δ), a larger thickness of the steel ring (ts), a smaller thickness of the carbon ring (tc), and a smaller height (ht). Also, it is preferable to have a slower cooling rate during the assembly process. It is observed that the coefficient of friction at the interface, μ, does not have any effect on fd. Finally, the process of an "expansion" fit does not contribute towards a reduction in fd, and hence is not worth the effort and cost.